Information processing device and information processing method

ABSTRACT

The present invention is relative with an information processing method for carrying out processing unit data in which one contents are handled as a data unit. When contents data are to be reproduced/output in succession, the tamper check processing for the next contents data, reproduced next to current contents data, being reproduced, is commenced at timing following the end of the processing of decryption and/or demodulation for the current contents data. This eliminates the time interval during which the processing of decryption/demodulation for the current contents data and the tamper check processing for the next contents data are carried out simultaneously in parallel to prevent the processing load caused by concurrent execution of the tamper check processing and the processing of decryption/demodulation from increasing.

TECHNICAL FIELD

This invention relates to an apparatus and a method for executingprocessing on unit data in which one contents are handled as a dataunit.

The present application contains subject matter related to JapanesePatent Applications JP 2003-119946 and JP 2003-119947, filed in theJapanese Patent Office on Apr. 24, 2003, the entire contents of whichbeing incorporated herein by reference.

BACKGROUND ART

Recently, AV (Audio and Video) contents data, such as audio data orvideo data, are encoded in some way or other prior to recording. Amongvarious species of such recording, there is widely known the encodingfor compression to provide data in a compressed form in accordance witha predetermined system. If contents data are encoded for compression,the data size in terms of contents as a unit is decreased, so that arecording medium of a finite size can be exploited efficaciously. On theother hand, the contents data can be downloaded over a network in ashorter time.

The encoding is also carried out for encryption. This encryption is usedin general for copyright protection. That is, for reproducing contentsdata, encoded for encryption, keys for decryption are afforded only onsuch occasions where the reproduction of the contents data is allowed.The contents data can be reproduced/output on decoding for encryptionwith the use of these keys.

As for the encoded contents key, there are occasions where the pluralcontents data exhibit continuity as regards the substance of thecontents. If, in such case, the contents are simply reproduced in order,the resulting reproduction output is simply self-completed from contentsdata to contents data, while continuity may not be afforded toneighboring contents data. The Japanese Laid-Open Patent Publication JP2002-112341 shows a technique in which contents data neighboring to eachother in the sequence of reproduction are encoded such as to maintaincontinuity of the reproduction/output.

If the configuration of the encoding technique, designed to affordcontinuity of the reproduction/output among plural contents data, asdescribed above, is used, it may be an occurrence that the continuity ofthe reproduction/output cannot be maintained under the followingconditions:

For example, it is a frequent occurrence in recent years that theprocessing of decoding for encryption as well as encoding forcompression described above is executed as software processing. In suchcase, the CPU, for example, executes the processing in accordance with aprogram for processing for decoding.

In such configuration, there are occasions wherein the CPU, carrying outprocessing of decoding of contents data to be currentlyreproduced/output, has to carry out another different processing inparallel with the processing of decoding.

In general, the processing of decoding of AV contents data is heavyprocessing retained to impose a high CPU take-up ratio. Now, supposethat the processing that has come to be carried out in parallel withthis processing of decoding is also a heavy processing with a ratherhigh CPU take-up ratio. In such case, a heavy load tends to be imposedon the CPU, with the result that the processing of decoding is retarded,with the result that the continuity of the reproduction/output cannot bemaintained. Under these conditions, there is a possibility that thereproduction/output is interrupted even within the contents data.

For combating these inconveniences, it may be contemplated to use a CPUwith a higher performance and a higher processing capability. However,from the considerations of costs, the usual practice is to use a CPUwith a processing capability that matches the system. Hence, if thelevel of the processing capability that fully assures e.g. theabove-described continuity of the reproduction output is redundant withthe system in use, it is undesirably not possible to strike an optimumbalance between the assurance of the performance and the cost.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a novel method andapparatus whereby it is possible to overcome the above-describedproblems inherent in the conventional technique.

It is more specific object of the present invention to provide a methodand an apparatus for information processing in which, when theprocessing of decoding is carried out under the conditions that the CPUused is of a certain processing capability, the CPU take-up ratio willbe lower than a certain value.

For accomplishing the above objects, the present invention provides aninformation processing apparatus comprising processing means forcarrying out at least a processing of decoding encoded unit data and apre-decoding processing related to the unit data, the pre-decodingprocessing being carried out prior to the processing of decoding,storage means where decoded data obtained on the processing of decodingare written and transiently stored, and outputting means from which thedecoded data stored in the storage means is continuously read out andoutput as data for reproduction/outputting. The processing meanscommences the processing of decoding of the unit data after the end ofthe pre-decoding processing related to the unit data.

The present invention also provides an information processing methodcomprising pre-decoding processing relevant to encoded unit data,processing of decoding for decoding the unit data after the end of thepre-decoding processing, processing of storage for transiently storingdecoded data obtained on processing for decoding, and outputtingprocessing for successively reading out the decoded data transientlystored by the processing of storage and for outputting the read-outdecoded data as data for representation/outputting.

Other objects and advantages of the present invention will becomeapparent from the following explanation of certain preferred embodimentsthereof especially when read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an illustrative configuration of arecording and/or reproducing apparatus according to the presentinvention.

FIG. 2 shows reproduction processing of encrypted contents according tothe present invention.

FIG. 3 is a timing chart showing a typical processing sequence in caseof continuous reproduction of the encrypted contents.

FIG. 4 is a timing chart showing a processing sequence in case ofcontinuous reproduction of encrypted contents embodying the presentinvention.

FIG. 5 is a timing chart showing the operations of reproductionprocessing in case of continuous reproduction of encrypted contents ofusual reproduction time by setting a buffer capacity to a usualcapacity.

FIG. 6 is a timing chart showing the operations of reproductionprocessing in case of continuous reproduction of encrypted contents ofshort reproduction time by setting a buffer capacity to a usualcapacity.

FIG. 7 is a timing chart showing typical operations of reproductionprocessing in case of continuous reproduction of encrypted contents ofshort reproduction time by setting a buffer capacity to short-timecontinuous reproduction.

FIG. 8 is an explanatory view showing another typical reproductionprocessing for encrypted contents according to the present invention.

FIG. 9 is a timing chart showing a processing sequence in case ofcontinuous reproduction of encrypted contents.

FIG. 10 is a timing chart showing typical operations for reproductionprocessing in case of continuous reproduction of encrypted contents,inclusive of fringe demodulation processing, with processing time withina usual range, by setting a buffer capacity to a usual capacity.

FIG. 11 is a timing chart showing typical operations for reproductionprocessing in case of continuous reproduction of encrypted contents,inclusive of fringe demodulation processing, by setting a buffercapacity to a usual capacity, with processing time outside a usualrange.

FIG. 12 is a timing chart showing typical operations for reproductionprocessing in case of continuous reproduction of encrypted contents,inclusive of fringe demodulation processing, with processing timeoutside a usual range, by setting a buffer capacity to a capacityconfigured to cope with long-time processing.

BEST MODE FOR CARRYING OUT THE INVENTION

An information processing apparatus, embodying the present invention,includes a CPU (Central Processing Unit) 11 for performing overallcontrol and calculation processing operations for a recording and/orreproducing apparatus 1, based on a program booted, as shown in FIG. 1.The CPU 11 takes charge of communication operations, mediated e.g. by anetwork, input/output operations for a user, reproduction or ripping ofcontents from recording media, storage of contents on a HDD 21, orcontrol operations therefor. This CPU 11 exchanges control signals ordata with different components of the circuitry over a bus 12.

In a ROM 13, operational programs, run by the CPU 11, program loaders, avariety of coefficients for calculations or parameters used in programs,are stored.

In a RAM 20, the program run by the CPU 11 is provisionally stored. TheRAM is also used as a data area or a task area necessary for the CPU 11to execute various processing operations. In the present embodiment,there may be provided an area as a buffer area 20 a as typical of thisdata area or task area. This buffer area 20 a may, for example, be anarea in which to store transiently as-decoded contents data inreproducing and outputting contents data read out from e.g. a recordingmedium loaded in a medium drive 19 or from the HDD 21.

The following explanation is made for a case where audio contents data,that may be recorded and/or reproduced for a recording and/orreproducing apparatus 1 of the present invention, is audio contentsdata.

An operating input unit 15 is a site comprised of a variety ofactuators, such as actuating keys, a jog dial or a touch panel, providedto a casing of the recording and/or reproducing apparatus 1. Meanwhile,a keyboard or a mouse for actuating the GUI (Graphical User Interface)may also be provided as the operating input unit 15. The operating inputunit 15 may also be a remote controller.

The information entered on the operating input unit 15 is processed in apredetermined manner by an input processor 14 and thence transmitted tothe CPU 11 as an operational command. The CPU 11 performs control orcalculations, as necessary, for producing operations as an apparatusresponsive to the input operating command.

As a display monitor 17, a display device, such as a liquid crystaldevice, is connected, for demonstrating various information materials.

When the CPU 11 sends the display information to a display processor 16,depending on various operating states, input states or the states ofcommunication, the display processor 16 demonstrates display data, assupplied, on the display monitor 17.

For example, in the instant embodiment, a GUI picture for managing andreproducing an audio file is demonstrated in accordance with a programfor reproducing and managing a ripped audio file.

The medium drive 19 for this case is a drive capable of managing andreproducing a predetermined recording medium. The medium drive 19 mayalso be a drive capable not only of reproducing but also of recording apredetermined recording medium.

Although there is no limitation to the recording media the medium drive19 can cope with, these recording media may also be a variety ofdisc-shaped recording media, such as CD, DVD or Mini-Discs. Or, therecording media may also be formed by memory devices, such as flashmemories. The media drive may also be separate drives, configured tocope with these media separately, and which are separately connected tothe bus 12.

For example, if the user has actuated the operating input unit 15, byway of issuing a command for reproduction by the medium drive 19, theCPU 11 commands the medium drive 19 to reproduce the medium. Responsivethereto, the medium drive 19 has access to specified data of therecording medium loaded thereon to read out the so accessed data.

In case the data thus read out are audio contents, the data are decodedby processing on the CPU 11, as necessary, and are thence transmitted toan audio data processor 24. The data are processed by the audio dataprocessor 24 with sound field processing, such as equalizing, volumeadjustment, D/A conversion or amplification, so as to be output via aloudspeaker 25.

The data reproduced by the medium drive 19 may also be stored in the HDD21, as audio data file, under control by the CPU 11. That is, the audiodata file, acquired by the so-called ripping, may be stored as contents.

The audio data file may be in the form of digital audio data with thesampling frequency of 44.1 kHz and a quantization step of 16 bits, inaccordance with the CD format, or in the form of compressed dataobtained on data compression in accordance with a preset system forsaving the capacity of the HDD 21. Although there is no limitation tothe compression system, the ATRAC (Adaptive Transform Acoustic Coding)system or the MP3 (MPEG Audio layer III) system, for example, may beused.

A tuner 27 is e.g. an AM-FM radio tuner, and demodulates broadcastsignals, received by an antenna 26, under control by the CPU 11. Ofcourse, the tuner may be a TV tuner, a BS tuner or a digital broadcasttuner.

The demodulated broadcast speech signals are processed in a presetmanner by the audio data processor 24, and output as broadcast speechover the loudspeaker 25.

A communication processor 22 encodes and decodes transmitted data andreceived data, respectively, under control by the CPU 11.

A network interface 23 sends transmitted data, encoded by thecommunication processor 22, to a predetermined apparatus, configured tocope with an external network, over a network. The network interface 23also delivers signals, transmitted over the network from the apparatus,configured to cope with the external network, to the communicationprocessor 22. This communication processor 22 transmits the informationreceived to the CPU 11.

The recording and/or reproducing apparatus 1 is not limited to theapparatus shown in FIG. 1 and may be any of a variety of other suitableapparatus.

For example, the recording and/or reproducing apparatus may also beprovided with an interface for peripheral equipment, in accordance withcommunication systems, exemplified by USB (Universal Serial Bus),IEEE1394 or Bluetooth.

The audio contents data, downloaded over the network from the networkinterface 23, or the audio contents data, transmitted via interfaces,exemplified by the USB or IEEE1394, may be stored in the HDD 21.

There may further be provided terminals used for connection to amicrophone or to an external headphone, a video output terminal,operatively associated with DVD reproduction, a line connectionterminal, or an optical digital connection terminal.

There may also be formed a PCMCIA slot or a memory card slot forenabling data exchange with external information processing apparatus oraudio apparatus.

As may be understood from the foregoing explanation, which refers toFIG. 1, the recording and/or reproducing apparatus 1 according to thepresent invention is able to reproduce and output audio contents data asspeech. For example, if contents data are recorded on a recordingmedium, loaded on the medium drive 19, the contents data, read out fromthe medium, may be reproduced and output. In addition, the contentsdata, stored in the HDD 21, may be read out, and the data, so read out,may be reproduced and output.

In addition, the present embodiment is configured so that audio contentsdata, encoded for compression in accordance with a predeterminedcompression encoding system and further encrypted in accordance with apredetermined encryption system, referred to below simply as ‘encryptedcontents’, may be reproduced and output as speech.

The processing sequence for reproducing and outputting these encryptedcontents as speech will now be explained with reference to FIG. 2. Inthis figure, there is shown a case where sole encrypted contents arereproduced and output. It is assumed that, for simplicity ofexplanation, the encrypted contents being reproduced are stored in theHDD 21.

It should be noted however that the processing of reproducing theencrypted contents according to the present invention, now explained,may comprehensively be applied to any case of reproducing encryptedcontents by the recording and/or reproducing apparatus 1 according tothe present invention, such as, for example, a case of reading out andreproducing the encrypted contents, recorded on a recording medium, or acase of reproducing the encrypted contents as acquired over the network.

As for the encrypted contents, stored in the HDD 21, and which are to bereproduced, tamper check processing is carried out, first of all, inorder to verify whether or not the data has been subjected to illicitdata tampering. This tamper check processing is carried out by the CPU11 in accordance with a program for reproducing the encrypted contents.The program for reproducing the encrypted contents is stored as it isinstalled on the HDD 21. In running this program, it is read out fromthe HDD 21 so as to be temporarily stored in the RAM 20.

If, on completion of the aforementioned tamper check processing, it isrecognized that no illicit data tampering has been done to the encryptedcontents, these contents, read out from the HDD 21 and sequentiallytransmitted, are processed with processing of decryption/demodulation.

This processing of decryption/demodulation is also carried out by theCPU 11 in accordance with the program for reproducing the encryptedcontents, and the processing for decryption is carried out on the dataof the encrypted contents transmitted from one preset processing unit toanother. The decrypted contents data, that is, data obtained ondecryption, are subjected to demodulation (decompression) in accordancewith a procedure reversed from the procedure for encoding bycompression. This yields decompressed digital audio data.

A data string, as digital audio data, obtained on processing fordecryptioni demodulation, is written in order, by processing for writingin the buffers, in a plurality of buffers, obtained on splitting abuffer area 20 a.

It is noted that the processing of decryption/demodulation is theprocessing for actually decrypting and decompressing the encryptedcontents to demodulate the digital audio data. In short, it is theprocessing of decryption and decompression. On the other hand, thetamper check processing is itself not decryption and is the processing,execution of which prior to decryption is indispensable.

The buffer area 20 a is provided with a plurality of buffers. Here, acase is shown in which there are provided three buffers 1 to 3. It isassumed that, for each of these plural buffers, the same data capacityis afforded. In actuality, each buffer is formed as a ring buffer.

The processing for writing in the buffers is carried out as follows: Ina stage prior to the start of the processing fordecryption/demodulation, the buffers 1 to 3 are in vacant states. Whenthe processing of decryption/demodulation is commenced and it is timefor writing data in the buffers, the data is first written in the buffer1. When data is stored in the buffer 1 to its full capacity, data iswritten in the buffer 2. When data is stored in the buffer 2 to its fullcapacity, data is written in the buffer 3. For confirmation, datawriting in the buffer 2 occurs at a rate faster than the data readoutrate from the buffer. The data written and stored in the buffers 1 to 3exhibit temporal continuity, provided that the operation is carried outin a usual manner. That is, the data thus written and stored arecontinuous data as the reproduced output sound. If, in the course of aprocess in which writing is commenced in the buffer 1 and sequentiallyexecuted in the next buffers 2 and 3, data is stored in the buffer 1 inmore than a predetermined volume, data commences to be read out, at apreset data rate, beginning from the data initially stored in the buffer1, by way of memory readout from the buffer area 20 a.

Turning to the buffer readout processing, when the entire data stored inthe buffer 1 has been read out, data stored in the buffer 2 is read out.The data stored in the buffer 2 are then read out. When the entire datastored in the buffer 2 has been read out, data stored in the buffer 3 isread out.

Turning to the buffer write processing, when the writing is completed upto the buffer 3, data is written as from the buffer 1 from which datahas been completely read out and which has now become void. In similarmanner, data is then written sequentially in the buffers 2 and 3, fromwhich data has been completely read out and which have now become void.

That is, as for the processing of writing in the buffers 1 to 3, thewriting repeatedly occurs in the order of the buffers 1, 2 and 3,specifically, data is written in the buffers in the vacant state, at apredetermined data rate.

As for data readout from the buffers 1 to 3, data are read out from thebuffers 1, 2 and 3, in this order, at a rate slower than the write rate,with a time delay corresponding to storage of a quantity of data notless than a predetermined quantity by data writing.

With this write/readout processing for the buffers 1 to 3, data isstored in at least one of the buffers 1 to 3, as long as there isproduced no so-called memory overflow or memory underflow, thus assuringcontinuity of reproduced data. If the readout operation is thatdescribed above, the write processing in the buffers is such that, incase data is stored in the totality of buffers, data writing isdiscontinued and, when the buffer in which writing is to be made firstin the write sequence has become void, data writing is commenced. Thatis, the operation may become intermittent, at least insofar as theprocessing of writing in the buffers is concerned.

In accordance with the above-described processing for writing/readoutfor the buffers, transfer processing to a reproducing/outputting systemis commenced in synchronism with start of readout of data from thebuffers.

This transfer processing to the reproducing/outputting system is carriedout by the CPU 11 in accordance with the program for reproducing theencrypted contents, and is such a processing in which data read out fromthe buffer is transmitted to a reproduction signal processing system(reproducing/outputting system) for reproducing/outputting the readoutdata.

The reproduction signal processing system (reproducing/outputtingsystem) in this case is the audio data processor 24 in the apparatusshown in FIG. 1. The transfer processing for the reproducing/outputtingsystem is such a one in which data read out from the buffers istransmitted over bus 12 at a desired data rate such that continuity ofaudio data to be reproduced and output will be maintained in the audiodata processor 24.

The processing of writing data in the buffers is the processing ofwriting digital audio data by processing of decryption/demodulation inthe buffers. The data readout by readout from the buffers is transferredto the audio data processor 24 by the transfer processing to thereproducing/outputting system. Thus, there is a time interval duringwhich the processing of decryption/demodulation occurs in parallel andsimultaneously with the transfer processing to thereproducing/outputting system.

The audio data processor 24 is continuously supplied with digital audiodata read out from the buffers as described above. The audio dataprocessor performs preset signal processing, inclusive of D/Aconversion, on the digital audio data, thus supplied thereto, with theresult that the data is ultimately output as speech from the loudspeaker25. It is noted that, as long as continuity of the digital audio data,supplied to the audio data processor 24, is maintained, continuity asspeech of the contents, output from the loudspeaker 25, may also bemaintained.

As may be understood from the above explanation, which refers to FIG. 2,it may be said that there are three basic processing operations to becarried out by the CPU 11 in accordance with the program configured forreproducing the encrypted contents in reproducing and outputting givenencrypted contents, that is, the reproduction processing configured forcoping with the encrypted contents, that is, tamper check processing;processing of decryption/demodulation; and transfer processing to thereproducing/outputting system. Since the tamper check processing checksfor authenticity of the substance of the data contents, based on whetheror not the data was tampered with, this check processing needs to becarried out at any rate in the pre-stage of the processing ofdecryption/demodulation. That is, when given contents are targeted, thetamper check processing and the processing of decryption/demodulationare not executed simultaneously, but the order of execution of thetamper check processing □ the processing of decryption/demodulation isto be observed. However, there are occasions where the processing ofdecryption/demodulation and the transfer processing to thereproducing/outputting system are executed simultaneously, parallel toeach other, as previously explained.

Meanwhile, the processing for writing in the buffers of the buffer area20 a is ancillary to the processing of decryption/demodulation, whilethe readout processing is ancillary to the transfer processing to thereproducing/outputting system.

It may be contemplated that the reproducing processing for coping withthe encrypted contents, in the continuous reproduction of the encryptedcontents, is usually carried out at an execution timing, shown forexample in the timing chart of FIG. 3.

The case of starting contents reproduction from the contents A andsubsequently carrying out the contents B in succession is taken as anexample for explanation.

If a command for starting the reproduction of the contents A isobtained, the tamper check processing, with the contents A as target, iscarried out first at a time point t1. Meanwhile, in the presentembodiment, the time needed for the tamper check processing isapproximately constant without dependency upon the substance of theencrypted contents. However, the time needed for the tamper checkprocessing may be varied from contents to contents depending on theparticular encryption system used.

When the tamper check processing, with the contents A as target, isfinished at a time point t2 when a certain time has elapsed as from thetime point t1, the processing of decryption/demodulation, with thecontents A as the target, commences as from this timing t2.

Responsive to start of the execution of the processing ofdecryption/demodulation, with the contents A as the target, theoperation of storing the digital audio data, obtained by thedemodulation processing, also commences. When certain time has elapsed,the stored capacity in the buffers exceeds a certain value, so thatreadout becomes possible. This timing is indicated by a time point t3.

Hence, the transfer processing to the reproducing outputting system,with the contents A as a target, commences at the time point t3. Thistransfer processing to the reproducing outputting system is theprocessing of transferring the digital audio data, read-out from thebuffers, to the reproducing/outputting system, that is, to the audiodata processor 24.

The outputting of the reproduction sound, as the contents A, commencesat this time point t3.

For example, the processing of decryption/demodulation for the encodeddata, as the contents A, comes to a close at a time point t5. At thistime point t5, the writing in the buffers of the digital audio data ofthe contents A, obtained by the processing of decryption/demodulation,also comes to a close. At this time, the digital audio data, which hasas yet not been read out, is stored in the buffers.

Hence, even after time point t5, the transfer processing to thereproducing/outputting system for the contents A is continued until theentire data stored in the buffers is read out. In this case, thetransfer processing to the reproducing/outputting system for thecontents A has come to a close at a time point t7 and, in keepingtherewith, the reproduction output sound as the contents A also comes toa close at this time point t7. From this it follows that thereproducing/outputting time period, during which the contents A arereproduced and output, is the time period as from time point t3 untiltime point t7.

The reproducing processing for coping with the encrypted contents forthe contents B, to be reproduced next in succession to the contents A,is carried out as follows:

For reproducing the contents A and B in succession, in this order, thestart timing of the transfer processing to the reproducing/outputtingsystem for the contents B needs to be contiguous to the end timing ofthe transfer processing to the reproducing/outputting system for thecontents A. That is, in this case, the transfer processing to thereproducing/outputting system for the contents B needs to be started asfrom the timing t7 as shown.

Hence, in order to assure that the readout processing from the bufferswill be stared as from the time point t7, the processing ofdecryption/demodulation for the contents B is to be commenced at a timepoint t6 which precedes the time point t7, as basic time point, by atime duration needed for storage of a preset quantity of digital audiodata.

Consequently, the tamper check processing for the contents B needs to beexecuted at a stage temporally previous to this time point t6.

Thus, in the case shown in FIG. 3, as a reasonable processing sequencefor such case, the tamper check processing for the contents B is carriedout in succession to the end of the tamper check processing for thecontents A. That is, in FIG. 3, the tamper check processing for thecontents A is terminated at the time point t2, and the tamper checkprocessing for the contents B is commenced at this time point t2. Thistamper check processing for the contents B is terminated at the timepoint t4.

It should be noted in this connection that, as a matter of actualprocessing for reproducing the encrypted contents, the tamper checkprocessing and the processing of decryption/demodulation, out of theabove three processing operations, namely the tamper check processing,processing of decryption/demodulation and the transfer processing to thereproducing outputting system, represent heavy processing with a highertake-up ratio for the CPU 11. The transfer processing to thereproducing/outputting system represents lighter processing, with a lowtake-up ratio for the CPU 11, because this processing simply issues acommand for transferring the digital audio data, read out from thebuffers, over bus 12, with the take-up ratio for the CPU 11 beingcorrespondingly low.

Turning now to the timing of the processing sequence, shown as anexample in FIG. 3, it is seen that, during the time period as from thetime point t2 until time point t4, the processing ofdecryption/demodulation for the contents A and the tamper checkprocessing for the contents B are executed simultaneously parallel toeach other.

That is, from the perspective of the CPU 11, the two processingoperations, retained to be high in the CPU take-up ratio, are carriedout simultaneously, thus accounting for the high actual CPU take-upratio.

With this state of processing by the CPU 11, during the above timeperiod of t2-t4, there is a risk that delay is caused to the processingoperations, carried out simultaneously, depending on the performance ofthe CPU 11. Hence, in the case of FIG. 3, for example, the processingspeed needed for the processing of decryption/demodulation for thecontents A cannot be maintained, thus possibly causing underflow in thebuffers and resultant inconveniences, such as interruption of the voiceof the reproduced output.

Moreover, there are occasions where a program of an application otherthan the application of reproducing encrypted contents is run on therecording and/or reproducing apparatus 1 according to the presentinvention. For example, since the recording and/or reproducing apparatus1 of the present embodiment has e.g. a networking function, it isprobable that an application such as a Web browser, exploiting thisfunction, or a mailer for transmitting/receiving an E-mail, is installedon the HDD 21, and booted as necessary.

If, when the reproducing processing program for the encrypted contentsand the other application programs, such as those described above, forexample, are being run, the state of high CPU take-up ratio, asindicated by the time period of t2 to t4, is produced, the probabilityis high that the interruption of the reproducing outputting speech, asdescribed above, is produced. Conversely, the operation of otherapplication programs becomes heavy, such that the operation may beslowed down.

Thus, in the processing sequence for the reproducing processing,configured for coping with the encrypted contents, the heavy processingoperations, retained to be high in the CPU take-up ratio, may give riseto undesirable effects on the operation of the apparatus, if theseoperations are carried out in parallel with the processing ofreproducing the encrypted contents.

Consequently, with the present embodiment, the processing for thereproduction processing for coping with the encrypted contents iscarried out as shown in FIG. 4. In the processing sequence, shown inFIG. 4, such a case in which reproduction is started from the contents Aas encrypted contents, and the contents B are reproduced in succession,is again taken as an example.

In this case, the timing for each of the tamper check processing,processing of decryption/demodulation and the transfer processing to thereproducing outputting system, for the contents A as target, is similarto that in FIG. 3.

The timing for each of the tamper check processing, processing ofdecryption/demodulation and the transfer processing to the reproducingoutputting system, for the contents B as target, is also similar to thatin FIG. 3, because the contents B need to be reproduced in succession tothe contents A.

With this in mind, the tamper check processing for the contents B, astarget, is commenced, in the present embodiment, at a time point t5,which is the time point of termination of the processing ofdecryption/demodulation for the contents A, as shown in FIG. 4.

That is, with the present embodiment, the program algorithm is such thatthe tamper check processing for the contents reproduced next will becarried out in succession to the processing of decryption/demodulationfor the contents currently reproduced/output.

The tamper check processing for the contents B by the above-describedprocessing sequence is carried out after completion of the processing ofdecryption/demodulation for the contents A, by taking advantage of thetime interval during which the digital audio data stored in the buffersare read out and reproduced/output by the transfer processing to thereproducing/outputting system for the same contents A.

In FIG. 4, the tamper check processing for the contents B is terminatedat a time point t6 when the processing of decryption/demodulation forthe contents B commences. This shows that it is sufficient if the tampercheck processing for the contents B comes to a close at the time pointt6 at the latest. In actuality, the tamper check processing for thecontents B may be terminated at a time point previous to the start timepoint of the processing of decryption/demodulation for the contents B.

With such processing sequence, the time period during which, in theconsecutive reproduction /outputting of the encrypted contents, theprocessing of decryption/demodulation and the tamper check processing,both of which are high in the CPU take-up ratio, are carried outsimultaneously, may be eliminated. This enables the CPU take-up ratio,configured to cope with reproduction of the encrypted contents, to beappreciably lower than in the conventional system, to avoid undesirableoperations in which the CPU take-up ratio becomes higher to render itimpossible to maintain continuity of the reproduction/output. On theother hand, certain allowance may be afforded to the CPU capacity whenother applications, for example, are run simultaneously.

It will be understood that, in the processing sequence, shown in FIG. 4,the timing of execution of the tamper check processing for the contentsreproduced next takes advantage of the operation of transiently storingthe decrypted/demodulated digital audio data in the buffers.

That is, the time period as from the time of termination of theprocessing of decryption/demodulation of the contents currentlyreproduced until the start of the tamper check processing for the nextcontents is a time period during which the digital audio data stored inthe buffers are read out and reproduced/output. Since this period issuch a period during which, as the reproducing processing for copingwith the encrypted contents, with the current contents as target, onlythe transfer processing to the reproducing outputting system for thecurrent contents is carried out, while the processing ofdecryption/demodulation is not carried out, the tamper check processingfor the next contents is carried out during this period.

Thus, in order that the termination of the tamper check processing forthe next contents and the consecutive reproduction of the next contentswill be carried out satisfactorily, it is sufficient that the timeduration as from the end of the processing of decryption/demodulationfor the current contents until readout of the digital audio data storedin the buffers to terminate the reproduction/outputting is longer thanthe time needed for the tamper check processing.

If, in the present embodiment, consecutive reproduction of the encryptedcontents, having ordinary presumable reproduction time, is presupposed,the capacity values of the respective buffers in the buffer area 20 aare set in order to assure that the next contents will be reproduced insuccession to the end of the tamper check processing of the samecontents.

The speech reproduction of the encrypted contents is started responsiveto start of the transfer processing to the reproducing/outputtingsystem, including buffer readout processing, after the processing ofdecryption/demodulation is started following the tamper check processingand a quantity of data in excess of a predetermined quantity is storedin the buffer. That is, the time interval until storage of more than apreset quantity of data in the buffer is a standby time during which thereproduction is not commenced.

Turning to the start of data readout from the buffers, responsive tostart of contents reproduction, in the present embodiment, if there areprovided three buffers 1 to 3, data writing in the buffer 1 to its fullcapacity is deemed to be the data storage in more than the predeterminedamount, and accordingly the readout from the buffers is commenced. Thus,if the capacities of the buffers 1 to 3 are increased, the quantity ofdata storage would be correspondingly increased. However, this is notdesirable because the standby time until the start of reproduction isthen protracted.

In light of the above, the usual capacities of the buffers 1 to 3 areset, in the present embodiment, in consideration of two conditions,namely

-   1. the condition that, on the premises that the encrypted contents,    having usual presumable reproduction time, are continuously    reproduced, the end of the tamper check processing for the next    contents and the consecutive reproduction of the next contents are    guaranteed, that is, the next contents are reproduced in succession    to the end of the tamper check processing for the same next contents    and-   2. the condition that the standby time until start of reproduction    is comprised within a range that is practically not of a problem, as    described above.

However, with the usual capacities of the buffers 1 to 3, there may beoccasions where the former condition may not be met, in case theencrypted contents to be reproduced in succession are of extremely shortduration, such that it may become impossible to maintain the continuityof the reproduction/output between the current contents and the nextcontents.

This point will now be explained with reference to Figs.5 and 6.

FIG. 5 shows a case where, of the encrypted contents A and B, reproducedcontinuously, at least the contents A, reproduced first, are ofordinarily presumable time duration, and the contents A and B arereproduced consecutively. In FIG. 5, the portions in the buffers 1 to 3,indicated by outline bars, represent the readout time period. On theother hand, the portions in the buffers 1 to 3, indicated by black bars,represent the write time period.

In this case, the tamper check processing is carried out for thecontents A during the period as from the time point t1 until time pointt2, and the processing of decryption/demodulation on the contents A iscarried out as from the time point t2. The writing in the buffer 1 iscarried out responsive to the start of the processing ofdecryption/demodulation on the buffer 1. This writing in the buffer 1comes to a close at a timing t3. The ensuing processing ofdecryption/demodulation is writing in the buffer 2, then in the buffer 3and then in the buffer 1, this sequence being repeated in the sameorder.

Responsive to the end of completion of writing in the buffer 1 at thetime point t3, the transfer processing to the reproducing/outputtingsystem for the contents commences at the time point t3. The readout fromthe buffer 1 is carried out at the same time point t3. This readout fromthe buffers is from the buffers 2 and 3 in this order, and then from thebuffer 1, this sequence being repeated in the same order.

It should be noted however that the write speed in the buffers is higherthan the readout speed. Thus, when the write/readout for the buffers iscarried out as regularly, such a state may be obtained in which, whenthe readout is carried out from a given buffer, for example, data isstored substantially steadily in the other buffers.

It is assumed that the processing of decryption/demodulation for thecontents A has come to a close e.g. at a timing t4, and that the writingof the digital audio data as the contents A also has come to a closee.g. with the writing in the buffer 3. If, in this case, the datareadout from the buffer 1 is executed until the time point t4, such astate is achieved, after time point 14, in which data is stored in thebuffers 2 and 3. Thus, by the transfer processing to thereproducing/outputting system as from the time point t4, the data readout from the buffer 2 is transmitted and reproduced/output, and the dataread out from the buffer 3 then is transmitted and reproduced/output.

If the unit reproducing time, corresponding to the usual recordingcapacity of the buffer 2, is Ts, as shown, readout of the contents A isenabled by the transfer processing to the reproducing/outputting systemduring the time represented by this unit reproducing time Ts×2.

Since the processing of decryption/demodulation for the contents isterminated at the time point t4, the tamper check processing for thecontents B commences at this time point t4.

It is now assumed that the time duration for tamper check processing ofthe present embodiment is roughly longer than the unit reproducing timeTs equivalent to the storage capacity for a buffer, but shorter than theunit reproducing time Ts×2.

Hence, the tamper check processing for the contents B is terminated at atime point t5 comprised within the time interval of t4 to t6corresponding to the unit reproducing time Ts×2.

In this case, the processing of decryption/demodulation of the contentsB is started at a time point t5, such that the transfer processing tothe reproducing outputting system for the contents B is commenced asfrom the time point t6 corresponding to the time of end of thereproducing period for the contents A. That is, the speech reproductionof the contents B commences at the time point t6, whereby the contents Aand B are reproduced as consecutive reproducing operation.

If, in consecutive reproduction of the contents A and B, the buffercapacities are set to ordinary values, and at least the contents A areof extremely short reproducing time, the reproducing operation mayoccasionally such a one shown in FIG. 6. In this case, the tamper checkprocessing for the contents A is carried out during the time period oft1-t2. In continuation to this time period, the processing ofdecryption/demodulation for the contents A is carried out as from thetime point t2. However, in this case, the processing ofdecryption/demodulation for the contents A comes to a close in a shortertime, in keeping with the shorter reproducing time for the contents A.

In such case, with the write/readout processing for the buffers 1 to 3,during the time of execution of the processing ofdecryption/demodulation for the contents A (t2-t4), in FIG. 6, it issolely the buffer 3 that holds data stored therein at time point t4.

That is, since the reproducing time for the contents A is extremelyshort, the processing of decryption/demodulation is also carried out foronly an extremely short time duration, as a result of which nosufficient differential (delta) between the data quantity stored by theprocessing of writing in the buffers and the data quantity read out bythe readout processing is obtained in the course of the execution of theprocessing of decryption/demodulation.

In this case, the time made available by the transfer processing to thereproducing outputting system for the contents A as from the time pointt4 is the unit reproducing time Ts corresponding to the data stored inthe buffer 3.

Hence, in such case, the transfer processing to thereproduction/outputting system for the contents A as from time point t4comes to a close at a time point t4 a after approximately the unitreproducing time Ts as from time point t4, and the outputting of thereproduced sound of the contents A ceases at this time point t4 a.

On the other hand, since the tamper check processing is a processingcontinuing for a time period longer than the unit reproducing time Ts,the tamper check processing for the contents B, started at time pointt4, keeps on to be executed even after the time point t4 a, and comes toa close e.g. at time point t5.

The processing of decryption/demodulation for the contents B commencesat this time point t5. The transfer processing to thereproducing/outputting system for the contents B is commenced, and hencethe speech output of the contents B is also commenced, after the timepoint t5 and at a time point t6 when the data writing in e.g. the buffer1 substantially comes to a close.

As a result of the above operations, there is produced a non-eproducingperiod (t4 a-t6 a) between the time point t4 a, corresponding to the endof the outputting of the reproduced speech of the contents A, and thetime point t6, corresponding to the beginning of the outputting of thereproduced speech of the contents B. That is, contents A and B cannot bereproduced in succession.

As typical of the case where continuous reproduction of the contents ofextremely short duration becomes necessary, there is, in addition to thecase where the actual reproduction time of the contents is extremelyshort, such a case where contents are to be edited by so-calledconnective or assembly editing.

That is, in editing the contents by connective editing, the trailing endportion of the leading contents and the leading end portion of thetrailing contents, each continuing only for a few seconds, are extractedto repeat continuous reproduction, in order to have the user confirm ifthe connected portion of the trailing end portion of the leadingcontents and the leading end portion of the trailing contents, specifiedto be connected to each other, are in meeting with the user's intention.

The reproducing operation of reproducing the trailing end portion of theleading contents and the leading end portion of the trailing contents isequivalent to the case shown in FIG. 6, in which contents B arereproduced in succession to the contents A with an extremely shortreproduction time. Hence, the risk is high that the trailing end portionof the leading contents and the leading end portion of the trailingcontents may not be reproduced consecutively.

If, in connective editing, it may be confirmed whether or not theconnected state is optimum, the trailing end portion of the leadingcontents and the leading end portion of the trailing contents must bereliably reproducible in succession.

Thus, if, in the instant embodiment of the present invention, thereproducing time at least of the encrypted contents to be reproducedfirst, out of the two encrypted contents to be reproduced successively,is less than a preset time length, such that successive reproduction maynot be guaranteed with the usual buffer capacity setting values, acertain buffer capacity, retained to be larger than the usual capacity,is set. This newly set buffer capacity is referred to below as the‘buffer capacity for successive reproduction for short time duration’.

This setting change of the buffer capacity may be implemented bychanging area setting of the buffers 1 to 3 in the buffer area 20 a inthe RAM 20, under control by the CPU 11. That is, if an areacorresponding to a capacity A is allocated to each of the buffers 1 to3, as usual buffer capacity, area allocation is made for each of thebuffers 1 to 3, in setting the buffer capacity for successivereproduction for short time duration, so that each of the buffers 1 to 3will be of a preset capacity B larger than the capacity A.

The timing chart of FIG. 7 shows the operations in which, as the buffercapacity is set to the buffer capacity for successive reproduction forshort time duration, the contents B are reproduced in succession to thecontents A having the short reproducing time, as in the case of FIG. 6.

In such case, the processing of decryption/demodulation is commenced asfrom the time point t2, in succession to the tamper check processing forthe contents A for the time period of t1-t2. As this processing ofdecryption/demodulation proceeds, writing is started, beginning from thebuffer 1 at the same time point t2. It is seen that, since the capacitylarger than the usual value is afforded to each of the buffers 1 to 3,the time needed until the end of the writing in the buffer 1 iscorrespondingly longer. Hence, the time duration as from the time pointt2 until the time point t3 when the transfer processing to thereproducing/outputting system for the contents A commences is longerthan the time duration of t2 to t3 shown in FIG. 6. In short, thestandby time until actually the speech commences to be reproduced andoutput, at the time of the start of reproduction, becomes longer.

In this case, such a state is shown in which, after a time point t4 whenthe processing of decryption/demodulation for the contents A, forexample, has come to a close, data is stored only in the buffer 3, outof the buffers 1 to 3. Hence, as from the time point t4, the operationof reading out the data stored in the buffer 3, with the progress of thetransfer processing to the reproducing/outputting system for thecontents A, and reproducing/outputting the so read-out data, is carriedout. This operation is carried out for a reproducing time TLcorresponding to the capacity of the buffer 3. Since the reproducingtime TL corresponds to the buffer capacity for successive reproductionfor short time duration, the reproducing time TL is longer than the unitreproducing time Ts related to the usual buffer capacity. However, thetime needed for the tamper check processing is substantially constant,without dependency on e.g. the reproducing time for the contents.

In this case, the tamper check processing for the contents B, carriedout as from the time point t4, comes to a close at the time point t5after a time duration approximately equal to that in FIG. 6. This timepoint t5 is well before timing t6 when the operation of reading out andreproducing/outputting data stored in the buffer 3 comes to a close, asshown. That is, in the present case, the tamper check processing for thecontents B is completed during the time the digital audio data for thecontents A are being reproduced/output. In this case, the processing ofdecryption/demodulation for the contents B is carried out as from thetime point t5 and, after lapse of a certain time as from time point t5,that is, at the time point t6, the transfer processing to thereproducing outputting system of the contents B is started as regularly,in place of the speech reproduction/outputting of the contents A, whichhas just come to a close. In short, the speech reproduction/outputtingof the contents A commences.

It will be appreciated that, by setting the other buffer capacity of avalue larger than the usual value, speech continuity may be maintainedeven in case of successive reproduction for encrypted contents includingencrypted contents of short reproduction time.

In the present embodiment, the buffer capacity is set to a usual valuefor regular cases. For the regular cases, when the encrypted contentsare consecutively reproduced, the reproducing time duration of theencrypted contents exceeds a certain preset value, so that it ispossible to maintain continuity in the reproduction, as explained withreference to FIG. 5.

Since the buffer capacity for these cases is set so that the standbytime until actual start of speech reproduction at the time of start ofreproduction will be in a tolerable range, the user has no alien feelingwith the standby time under the usual use state.

However, the buffer capacity is switched to the buffer capacity forsuccessive reproduction for short time duration on the occasion ofconfirmative reproduction for the connecting position in the connectiveediting as previously explained, or consecutive reproduction ofencrypted contents in succession to the encrypted contents of anextremely short reproduction time shorter than a certain presetreproduction time. This assures continuity of reproduction even in caseof reproducing the encrypted contents of extremely short time durationof reproduction, as shown in FIG. 7.

As may be seen from the time duration as from the time point t2 untiltime point t3, shown in FIG. 7, the buffer capacity for successivereproduction for short time duration is larger than the usual buffercapacity, with the result that the reproduction standby time as from thestart of reproduction processing until start of the speech outputting isprotracted. However, the connective editing or reproduction of encryptedcontents with extremely short reproduction time represents specializedreproduction, distinct from the reproduction of usual encryptedcontents, and is carried out less frequently. That is, the reproductionstandby time is protracted transiently only on occasions, retained to bespecial occasions, thus raising no particular problem in the actual usethe recording and/or reproducing apparatus 1.

Such a case will now be explained in which relevant data other than theaudio data, termed fringe data, is annexed to each of the encryptedcontents as audio data.

The fringe data, annexed as the relevant data to the encrypted contents,may be exemplified by picture data, such as album jackets, pertinent torelated encrypted contents, picture data for representing artist’profiles or liner notes, and text data.

These fringe data are correlated with the encrypted contents as audiodata and supervised in this state. These fringed data, thus managed, arestored as files distinct from the files of the encrypted contents asaudio data. A plural number of these fringe data may also be associatedwith sole encrypted contents, in the form of, for example, data ofplural album jackets or data of plural lyrics.

If these fringe data are picture data, for example, the data arecompressed in accordance with a preset picture compression system, andfurther are encoded for encryption.

If, in reproducing the encrypted contents, the fringe data are decoded,pictures of album jackets or the lyrics may be demonstrated on thedisplay monitor 17 when the encrypted contents are reproduced/output asspeech.

Referring to FIG. 8, the processing sequence for outputting theencrypted contents, along with the fringe data, annexed thereto, asspeech, will now be explained with reference to FIG. 8, in which thecase of reproducing/outputting sole encrypted contents is shown. It isassumed, for simplicity of explanation, that the encrypted contentsbeing reproduced are stored on the HDD 21.

It should be noted that the reproduction processing for the encryptedcontents, as now explained, is generally applicable to variable casesfor reproducing encrypted contents by the recording and/or reproducingapparatus 1 shown in FIG. 1, e.g. a case where encrypted contentsrecorded on a recording medium are read out by the medium drive 19 andreproduced, or a case where encrypted contents acquired over a networkare reproduced.

Before decoding the encrypted contents for reproduction, recorded on theHDD 21, the decoding of the encryption of the fringe data anddemodulation (decompression) of the encoding thereof for compression,referred to below as processing for fringe demodulation, are carriedout.

This processing for fringe demodulation is carried out by the CPU 11 inaccordance with the program for reproducing the encrypted contents. Thatis, the processing for fringe demodulation is carried out not byhardware, but by software. Meanwhile, the program for reproducing theencrypted contents is installed and stored on the HDD 21. When theprogram is to be run, it is read out from the HDD 21 so as to betemporarily stored in the RAM 20.

For this processing, the HDD 21 is instructed to read out target fringedata. Responsive thereto, the fringe data is read out from the HDD 21and thence transmitted over bus 12 to the CPU 11. The CPU 11 performsthe processing of decoding the encryption of the transferred data, asthe RAM 20 is utilized as a work area. The decrypted fringe data is inthe form e.g. of a picture encoded for compression, and hence issubjected to decompression which is the reverse of the encoding forcompression. The fringe data, thus demodulated, is held e.g. on the RAM20.

In the present embodiment, the demonstration/outputting of the fringedata is carried out e.g. simultaneously with start of speechreproduction of the encrypted contents. However, since the processing ofdecoding the fringe data represents relatively heavy processing for theCPU 11, it is difficult to execute the processing of decoding the fringedata in time for the start of the speech reproduction/outputting of thedecrypted version of the encrypted contents, even if the processing ofdecoding the fringe data is carried out simultaneously with theprocessing of decryption/demodulation of the encrypted contents.

For this reason, the fringe data is decoded, in the present embodiment,prior to decoding the encrypted contents. In case the fringe data areas-decoded data, it is only sufficient to transmit the fringe data toe.g. the display processor 16 for demonstration. Thus, the fringe datamay be displayed/output, simultaneously with start of the speechreproduction/outputting of the encrypted contents, by transmitting theas-decoded fringe data to the display processor 16 in synchronism withthe speech reproducing/outputting timing of the encrypted contents.

When the above-described processing for fringe demodulation is retainedto have come to a close, the processing of decryption/demodulation iscarried out for the encrypted contents, which are read out andsequentially transmitted from the HDD 21.

The processing of decryption/demodulation is carried out by the CPU 11in accordance with the program for reproducing the encrypted contents.Specifically, the CPU decodes the encryption of data of the encryptedcontents, transmitted thereto, from one preset processed data unit toanother. The CPU also demodulates (decompresses) the decoded contentsdata matched to the compression encoding system used. This yieldsas-decompressed digital audio data.

The data string, as digital audio data, thus obtained ondecryption/demodulation, is sequentially written, by buffer writeprocessing, in the plural buffers, obtained on splitting the buffer area20 a.

It should be noted that the processing of decryption/demodulation is theprocessing of demodulating the digital audio data by decrypting anddecompressing the encrypted contents to yield demodulated digital audiodata, that is, the processing of decoding the encoding for encryptionand decoding the encoding for compression. On the other hand, theprocessing for fringe demodulation is the processing of demodulating theinformation which itself is not contents data as audio but which isneeded as ancillary data in reproducing/outputting the contents data.

Meanwhile, in the present embodiment, as in the recording and/orreproducing apparatus, described above, plural buffers are provided inthe buffer area 20 a, as shown in FIG. 8. Here, three buffers 1 to 3 areprovided. Moreover, it is assumed that the capacities of these buffersare the same, and that, in actuality, the buffers are formed as a ringbuffer.

In such case, the processing for writing in the buffers is carried outas follows:

In a stage prior to the start of the processing ofdecryption/demodulation, the buffers 1 to 3 are all in the vacantstates. When the processing of decryption/demodulation has commenced,and it is timing for writing data in the buffers, data is written firstin the buffer 1. When data has been written in the buffer 1 to its fullcapacity, data is written in the buffer 2 and, when data has beenwritten in the buffer 2 to its full capacity, data is written in thebuffer 3. For confirmation sake, data writing in the buffers is carriedout at a rate higher than the data readout rate from the buffers. On theother hand, data written and stored in the buffers 1 to 3 exhibittemporal continuity under ordinary conditions. That is, the data thuswritten and stored are continuous data in terms of the reproduced outputsound.

If, in the course of a process in which writing is commenced in thebuffer 1 and sequentially executed in the next buffers 2 and 3, data isstored in the buffer 1 in more than a predetermined volume, datacommences to be read out, at a preset data rate, beginning from the datainitially stored in the buffer 1, by way of performing memory readoutfrom the buffer area 20 a.

Turning to the readout processing from the buffers, when the entire datastored in the buffer 1 has been read out, data stored in the buffer 2 isread out. The data stored in the buffer 2 are then read out. When theentire data stored in the buffer 2 has been read out, data stored in thebuffer 3 is read out.

Turning to the processing for writing in the buffers, when the writingis completed up to the buffer 3, data is written as from the buffer 1from which data has been completely read out and which has now becomevoid. In similar manner, data is then written sequentially in thebuffers 2 and 3, from which data has been completely read out and whichhave now become void.

That is, as for the processing of writing in the buffers 1 to 3, thewriting repeatedly occurs in the order of the buffers 1, 2 and 3,specifically, data is written in the buffers in the vacant state, at apredetermined data rate.

As for data readout from the buffers 1 to 3, data are read out from thebuffers 1, 2 and 3, in this order, at a rate slower than the write rate,with a time delay corresponding to storage of a quantity of data notless than a predetermined quantity by data writing.

With this write/readout processing for the buffers 1 to 3, data isstored in at least one of the buffers 1 to 3, as long as there isproduced no so-called memory underflow, thus assuring continuity ofreproduced data. If, in the readout operation described above, the writeprocessing in the buffers is such that, in case data is stored in thetotality of buffers, data writing is discontinued and, when the bufferin which writing is to be made first in the write sequence has becomevoid, data writing is commenced. That is, the operation may becomeintermittent, at least insofar as the processing of writing in thebuffers is concerned.

In accordance with the above-described processing for writing/readoutfor the buffers, transfer processing to a reproducing/outputting systemis commenced in synchronism with start of readout of data from thebuffers.

This transfer processing to the reproducing/outputting system is carriedout by the CPU 11 in accordance with the program for reproducing theencrypted contents, and is such a processing in which data read out fromthe buffer is transmitted to a reproduction signal processing system(reproducing/outputting system) for reproducing/outputting the readoutdata.

The reproduction signal processing system (reproducing/outputtingsystem) in this case is the audio data processor 24 in the apparatusshown in FIG. 1. The transfer processing for the reproducing/outputtingsystem is such a one in which data read out from the buffers istransmitted over bus 12 at a desired data rate such that continuity ofaudio data to be reproduced and output will be maintained in the audiodata processor 24.

The processing of writing data in the buffers is the processing ofwriting digital audio data by processing of decryption/demodulation inthe buffers. The data read out from the buffers is transferred to theaudio data processor 24 by the transfer processing to thereproducing/outputting system. Thus, there is a time interval duringwhich the processing of processing of decryption/demodulation occurs inparallel and simultaneously with the transfer processing to thereproducing/outputting system.

The audio data processor 24 is continuously supplied with digital audiodata read out from the buffers as described above. The audio dataprocessor performs preset signal processing, inclusive of D/Aconversion, on the digital audio data, thus supplied thereto, such thatthe data is ultimately output as speech from the loudspeaker 25. It isnoted that, as long as continuity of the digital audio data, supplied tothe audio data processor 24, is maintained, continuity as speech of thecontents, output from the loudspeaker 25, may also be maintained.

Meanwhile, the data transfer processing to the display processor 16 forreproducing/outputting (demonstrating/outputting) the fringe data,demodulated by the processing for fringe demodulation, may be carriedout at a start timing substantially concurrent as the transferprocessing to the reproducing/outputting system for the above-mentionedaudio data, although such is not specifically shown in FIG. 8.

As may be understood from the above explanation, which refers to FIG. 8,it may be said that there are three basic processing operations(reproduction processing operations for coping with the encryptedcontents) to be carried out by the CPU 11 in accordance with the programfor reproducing the encrypted contents in reproducing and outputtinggiven encrypted contents, that is, processing for fringe demodulationincluding reproduction processing for coping with encrypted contents),processing of decryption/demodulation, and transfer processing to thereproducing/outputting system. The processing for fringe demodulation isthe processing for demodulating the fringe data such as pictures ofalbum jackets relating to the contents. As for this processing forfringe demodulation, it is prescribed that the fringe data shall bedecoded to a state enabling the data to be reproduced/output, for e.g.display, before reproduction/outputting of the speech as contentscommences. The processing for fringe demodulation in such case thereforeis to be carried out necessarily in a pre-stage to the processing ofdecryption/demodulation. In short, as long as one given contents are atarget, the processing for fringe demodulation for the contents and theprocessing of decryption/demodulation for the contents are not carriedout simultaneously, but the executing sequence of the processing forfringe demodulation□ processing of decryption/demodulation is to beobserved. However, there are occasions where the processing for fringedemodulation and the transfer processing to the reproducing outputtingsystem are carried out simultaneously in parallel, as described above.

It is noted that the buffer write processing for the buffer area 20 a isancillary to the processing of decryption/demodulation, while thereadout processing is ancillary to the transfer processing to thereproducing/outputting system.

With the sequence of reproduction processing, configured to cope withthe given one encrypted contents, shown in FIG. 8, as premises, thereproduction processing, configured to cope with encrypted contents, incase of successive reproduction of encrypted contents, will now beexplained with reference to the timing chart of FIG. 9.

Here, a case of commencing contents reproduction from the contents A,and then reproducing the contents B in succession, is taken as anexample for explanation.

In case a command for starting the reproduction of the contents A isreceived, the processing for fringe demodulation for the contents A isfirst carried out at a time point t1.

The time needed for the processing for fringe demodulation is made todiffer depending on the particular fringe data to be demodulated. Forexample, the picture size or the resolution of the fringe data in theinstant embodiment is specifically not unified. Hence, the time neededfor the processing for fringe demodulation for the individual fringedata differs depending on the picture size or the resolution thereof.

The number of the fringe data to be annexed to one given encryptedcontents may be plural, as discussed previously. Since there is also noparticular limitation to the number of the fringe data to be related toone contents, the number of files as annexed fringe data differs fromencrypted contents to encrypted contents. Consequently, the time neededfor the processing for fringe demodulation differs with the number ofthe fringe data to be demodulated.

It is assumed that the processing for fringe demodulation for thecontents A has come to a close at a time point t2 when certain time haselapsed as from the time point t1. The processing ofdecryption/demodulation for the contents A is made to commence at thistime point t2.

The operation of storing the digital audio data, obtained by thedemodulation processing, in the relevant buffer of the buffer area 20 a,is commenced responsive to the start of the processing ofdecryption/demodulation for the contents A. Readout from the buffer areabecomes possible after lapse of certain time when the stored capacity inthe buffer exceeds a preset quantity. This timing is indicated by a timepoint t3.

Thus, the transfer processing to the reproducing/outputting system forthe contents A is commenced at the time point t3. This transferprocessing is the processing of transferring the digital audio data,read out from the buffer, to the audio data processor 24 as thereproducing/outputting system.

The outputting of the reproduced sound, as the contents A, commences atthis time point t3.

For example, the processing of decryption/demodulation of the encodeddata as the contents A comes to a close at a time point t4. At this timepoint t4, writing in the buffer of digital audio data of the contents A,obtained on decryption/demodulation, also comes to a close. At thistime, the digital audio data, not read out as yet, are stored in thebuffer.

Hence, the transfer processing to the reproducing/outputting system forthe contents A is continued, even after the time point t4, until thetotality of the data stored in the buffer is read out. In this case, thetransfer processing to the reproducing/outputting system for thecontents A comes to a close at a time point t6 and, in keepingtherewith, the reproduced/output sound as the contents A is to come to aclose at the time point t6. From this it follows that thereproducing/outputting time period, during which the contents A arereproduced and output, is the time period as from time point t3 untiltime point t6.

The reproducing processing for coping with the encrypted contents forthe contents B, to be reproduced next in succession to the contents A,is carried out as follows:

For reproducing the contents A and B in succession, in this order, thestart timing of the transfer processing to the reproducing/outputtingsystem for the contents B needs to be contiguous to the end timing ofthe transfer processing to the reproducing/outputting system for thecontents A. That is, in this case, the transfer processing to thereproducing/outputting system for the contents B needs to be started asfrom the timing t6 as shown.

Hence, in order to assure that the readout processing from the bufferswill be stared as from the time point t6, the processing ofdecryption/demodulation for the contents B is to be-commenced at-a timepoint t5, which precedes the time point t6, as basic time point, by atime duration necessary for storage of a preset quantity of digitalaudio data.

For this reason, the processing for fringe demodulation for the contentsB needs to be carried out in a pre-stage temporally forward of this timepoint t5.

Thus, in the case shown in FIG. 9, the processing for fringedemodulation for the contents B is carried out in succession to the endof the processing of decryption/demodulation for the contents A, as aprocessing sequence in such case. That is, the processing ofdecryption/demodulation for the contents A has come to a close at thetiming t4 in FIG. 9, and the processing for fringe demodulation for thecontents B is commenced at this time point t4.

The processing for fringe demodulation for the contents B is to becompleted by the time point t4 when the processing ofdecryption/demodulation for the contents B commences.

Meanwhile, it may be conjectured that the timing for starting theprocessing for fringe demodulation for the contents B may be the timingdirectly following the end of the processing for fringe demodulation forthe contents A. That is, the processing for fringe demodulation for thecontents B may be started at a timing t2, as indicated by a broken linerectangle in FIG. 9.

This means that, as for the processing for fringe demodulation, theprocessing for fringe demodulation of the encrypted contents, reproducednext, is to be carried out next to the processing for fringedemodulation of the encrypted contents currently reproduced. With suchprocessing timing for the processing for fringe demodulation, theprocessing for fringe demodulation may be completed in a pre-stage ofthe processing of decryption/demodulation of the encrypted contents inquestion.

It should be noted in this connection that, as a matter of actualprocessing for reproducing the encrypted contents, the processing offringe demodulation and the processing of decryption/demodulation, outof the above three processing operations, namely the processing forfringe demodulation, processing of decryption/demodulation and thetransfer processing to the reproducing outputting system, representheavy processing with a higher take-up ratio for the CPU 11. Conversely,the transfer processing to the reproducing/outputting system representslighter processing, with a low take-up ratio for the CPU 11, becausethis processing simply issues a command for transferring the digitalaudio data, read out from the buffers, over bus 12, with the take-upratio for the CPU 11 being correspondingly low.

If the processing for fringe demodulation of the encrypted contents,reproduced next, is to be carried out in succession to the processingfor fringe demodulation of the encrypted contents, currently reproduced,as described above, there is produced a time period during which theprocessing of decryption/demodulation for the contents A and theprocessing for fringe demodulation for the contents B are carried-outconcurrently after time point t2. That is, from the perspective of theCPU 11, the two processing operations, retained to be high in the CPUtake-up ratio, are carried out during this time simultaneously, thusaccounting for the considerably high actual CPU take-up ratio.

With this state of processing by the CPU 11, there is a risk that delayis caused to the processing operations, carried out simultaneously,depending on the performance of the CPU 11. Hence, the processing speedneeded for the processing of decryption/demodulation for the contents Acannot be maintained to cause underflow in the buffers, thus possiblycausing inconveniences, such as interruption of the voice of thereproduced output.

Moreover, there are occasions where a program of an application otherthan the application of reproducing encrypted contents is run on therecording and/or reproducing apparatus 1 according to the presentinvention. For example, since the recording and/or reproducing apparatus1 of the present embodiment has e.g. a networking function, it isprobable that an application such as a Web browser, exploiting thisfunction, or a mailer for transmitting/receiving an E-mail, is installedon the HDD 21, and booted for operations, as necessary.

If, when the reproducing processing program for the encrypted contentsand the other application programs, such as those described above, forexample, are run, the state of a high CPU take-p ratio, as indicated bythe time period of t2 to t4, is produced, the probability is high thatinterruption of the reproduced output speech, as described above, isproduced. Conversely, the operation of other application programs maybecome heavy, such that the operation may be slowed down.

Thus, in case plural heavy processing operations, retained to be high inthe CPU take-up ratio, are carried out simultaneously in the processingsequence for the reproducing processing for coping with the encryptedcontents, it may be feared that undesirable effects may be produced inthe operations of the apparatus.

Hence, in the present embodiment, the processing for fringe demodulationfor the contents B is made to commence at a time point t4 as the endtime point of the processing of decryption/demodulation for the contentsA.

That is, in the present embodiment, the program algorithm is set so thatthe processing for fringe demodulation for the contents reproduced nextwill be carried out in succession to the processing ofdecryption/demodulation for the contents currently reproduced/output.

The processing for fringe demodulation for the contents B by theabove-described processing sequence is carried out after completion ofthe processing of decryption/demodulation for the contents A, by takingadvantage of the time during which the digital audio data stored in thebuffers are read out and reproduced/output by the transfer processing tothe reproducing/outputting system for the same contents A.

In the processing sequence, shown in FIG. 3, the processing for fringedemodulation for the contents B is terminated at a time point t5 whenthe processing of decryption/demodulation for the contents B commences.This shows that it is sufficient if the processing for fringedemodulation for the contents B comes to a close at the time point t5 atthe latest. In actuality, the processing for fringe demodulation for thecontents B may be terminated at a start time point temporally forward ofthe start of the processing of decryption/demodulation for the contentsB.

With such processing sequence, the time period during which, in theconsecutive reproduction/outputting of the encrypted contents, theprocessing of decryption/demodulation and the processing for fringedemodulation, both of which are high in the CPU take-up ratio, arecarried out simultaneously, may be eliminated. In this manner, the CPUtake-up ratio, designed to cope with consecutive reproduction of theencrypted contents, may be appreciably lower than in the conventionalsystem.

Thus, it is possible to avoid undesirable operations that the CPUtake-up ratio becomes high to render it impossible to maintaincontinuity of the reproduction output. On the other hand, certainallowance may be afforded to the CPU capacity when other applications,for example, are run simultaneously.

Meanwhile, the setting of the timing of execution of the processing forfringe demodulation for the next contents reproduced, in the presentembodiment, shown in FIG. 9, is enabled on the premises that theoperation of transiently storing the digital audio data decrypted anddemodulated in the buffer is carried out.

That is, the time period as from the time of end of the processing ofdecryption/demodulation of the contents currently reproduced until thestart of the processing of decryption/demodulation for the next contentsis the time period when the digital audio data stored in the buffer isread out and reproduced/output. Since this time period is such a periodduring which only the transfer processing to the reproducing/outputtingsystem for the current contents is carried out without carrying out theprocessing of decryption/demodulation, the processing for fringedemodulation for the next contents is carried out during this period.

Thus, for satisfactory execution of the termination of the processingfor fringe demodulation for the next contents and the reproduction ofthe next contents contiguous thereto, it is sufficient that the timeduration as from the end of the processing of decryption/demodulationfor the current contents until readout of the digital audio data storedin the buffers to terminate the reproduction/outputting is longer thanthe time needed for the processing for fringe demodulation.

If, in the present embodiment, an ordinary presumable time interval ispresupposed as the time duration necessary for demodulating the fringedata, the capacity values of the respective buffers in the buffer area20 a are set so that reproduction of the next contents will occur insuccession to the end of the reproduction of the next contents.

As will be apparent from the previous explanation, the speechreproduction of the encrypted contents is commenced responsive to thestart of the transfer processing to the reproducing/outputting system,inclusive of the buffer readout processing, after start of theprocessing for decryption/demodulation following the processing forfringe demodulation, and a quantity of data in excess of a predeterminedquantity is stored in the buffer. That is, the time interval untilstorage of more than a preset quantity of data in the buffer is astandby time during which the reproduction is not commenced.

Turning to data readout from the buffers, related to start of contentsreproduction, in the present embodiment, if there are provided threebuffers 1 to 3, data writing in the first buffer 1 to its full capacityis deemed to be the data storage in more than the predetermined amount,and accordingly the readout from the buffers is commenced. If thecapacities of the buffers 1 to 3 are increased, the quantity of datastorage would be correspondingly increased. However, this is notdesirable because the standby time until the start of reproduction isthen protracted.

In light of the above, the usual capacities of the buffers 1 to 3 areset, in the present embodiment, in consideration of two conditions,namely

-   1. the condition that, on the premises that the processing time    duration is of the conceivable ordinary value for the processing for    fringe demodulation, the end of the processing for fringe    demodulation for the next contents and the consecutive reproduction    of the next contents are guaranteed, and-   2. the condition that the standby time until start of reproduction    is comprised within a range that is practically not of a problem, as    described above.

However, there are occasions where the time duration necessary forprocessing for fringe demodulation exceeds the range retained to be ausual range. In such case, the first condition cannot be guaranteed withthe usual capacities of the buffers 1 to 3, such that it may becomeimpossible to maintain the continuity of the reproduction/output betweenthe current contents and the next contents.

This point will now be explained with reference to FIGS. 10 and 11.

FIG. 10 shows a case where, in reproducing the encrypted contents A andB, which are to be reproduced successively, at least the contents B,reproduced next to the contents A, are of normally presumable timeduration, and the contents A and B are reproduced satisfactorily insuccession. In FIG. 10, the portions in the buffers 1 to 3, indicated byoutline bars, represent the readout time period. On the other hand, theportions in the buffers 1 to 3, indicated by black bars, represent thewrite time period.

In this case, the processing for fringe demodulation is carried out forthe contents A during the period as from the time point t1 until timepoint t2, and the processing of decryption/demodulation on the contentsA is carried out as from the time point t2. The writing in the buffer 1occurs responsive to the start of the processing ofdecryption/demodulation for the contents A. This writing in the buffer 1comes to a close at a timing t3. The ensuing processing ofdecryption/demodulation is writing in the buffer 2, then in the buffer 3and then in the buffer 1, this sequence being repeated in the sameorder.

Responsive to the completion of writing in the buffer 1 at the timepoint t3, the transfer processing to the reproducing/outputting systemfor the contents A commences at the time point t3. The readout from thebuffer 1 is carried out at the same time point t3. This readout from thebuffers is from the buffers 2 and 3, where data have already beenstored, in this order, and then from the buffer 1, this sequence beingrepeated in the same order.

It should be noted however that the write speed in the buffers is higherthan the readout speed. Thus, when the write/readout for the buffers iscarried out as regularly, such a state is obtained in which, forexample, when the readout is carried out from a given buffer, data isstored substantially steadily in the other buffers.

It is noted that the processing of decryption/demodulation for thecontents A comes to a close e.g. at a timing t4, and that the writing inthe buffer of the digital audio data as the contents A comes to a closee.g. with the writing in the buffer 3.

If, in this case, the data readout from the buffer 1 is executed untilthe time point t4, such a state is achieved, after time point 14, inwhich data is stored in the buffers 2 and 3. Thus, by the transferprocessing to the reproducing/outputting system as from the time pointt4, the data read out from the buffer 2 is transmitted andreproduced/output, and the data read out from the buffer 3 then istransmitted and reproduced/output.

If the unit reproducing time, corresponding to the usual recordingcapacity of the buffer 2, is Ts, as shown, readout of the contents A,following the end of the processing of decryption/demodulation for thecontents A at the time point t4, is enabled by the transfer processingto the reproducing/outputting system during the time represented by thisunit reproducing time Ts×2.

Since the processing of decryption/demodulation for the contents A isterminated at the time point t4, the processing for fringe demodulationfor the contents B is started at this time point t4.

It is now assumed that the time needed for the processing for fringedemodulation for the contents B is roughly longer than the unitreproducing time Ts equivalent to the storage capacity for a givenbuffer but shorter than the unit reproducing time Ts×2.

Hence, the processing for fringe demodulation for the contents B isterminated at a time point t5 comprised within the time interval of t4to t6 corresponding to the unit reproducing time Ts×2.

In this case, the processing of decryption/demodulation of the contentsB is started at a time point t5, such that the transfer processing tothe reproducing outputting system for the contents B is commenced asfrom the time point t6 corresponding to the time of end of thereproducing period for the contents A. That is, the speech reproductionof the contents B commences at the time point t6. It may be seen fromthis that contiguous reproducing operations for the contents A and B areachieved.

If conversely the processing time needed for the-processing for fringedemodulation for the contents B has become longer to exceed the usualrange, in consecutive reproduction of the contents A and B, with thebuffer capacities set to usual values, the reproduction processing maybe such a one shown in FIG. 11.

In this case, the processing for fringe demodulation for the contents Ais carried out during the time interval t1 to t2. In succession thereto,that is, at a time point t2, the processing of decryption/demodulationfor the contents A is started at the time point t2 and comes to a closeat a time point t4, as in FIG. 10.

In this case, such a state is obtained in which, at the time point t4,data are stored in the buffers 2 and 3. By the transfer processing tothe reproducing outputting system, carried out as from the time pointt4, data read out from the buffer 2 is first transmitted andreproduced/output, and data read out from the buffer then is transmittedand reproduced/output. Hence, the transfer processing to the reproducingoutputting system, carried out for the contents A as from the time pointt4, comes to a close after time of Ts×2 as from the time point t4, thatis, at a time point t6. At this time point, the output of the reproducedsound for the contents A ceases. As for this respect, there is nodifference from the case of FIG. 10.

In the present case, the processing for fringe data demodulation for thecontents B is retained to take the processing time in excess of theusual range. Hence, the time point t5, as a time point of the end of theprocessing for fringe demodulation for the contents B, commenced at thetime point t4, is temporally backward of the time point t6 when thetransfer processing to the reproducing/outputting system for thecontents A comes to a close.

The processing of decryption/demodulation for the contents B can bestarted only after the end of the processing for fringe demodulation forthe contents B. Consequently, the processing of decryption/demodulationfor the contents B is started at the time point t5, which is the endpoint of the processing for fringe demodulation for the contents B. Thetransfer processing to the reproducing outputting system for thecontents B is commenced after certain time lapse from the time point t5,or at a time point t6 a. That is, the outputting of the reproduced soundof the contents B commences at the time point t6 a.

With the above-described sequence of operations, there is produced anon-reproducing time as from the time point t6 for the end of thetransfer processing to the reproducing/outputting system for thecontents A until the start of the transfer processing to thereproducing/outputting system for the contents B at a time point t6 a.That is, the contents A, B cannot be reproduced in succession.

In case the time needed for processing for fringe demodulation hasbecome longer than the usual range, the processing for fringedemodulation can be carried out despite the fact that the readout ofcontents data prior to storage in the buffers has come to a close todiscontinue the outputting of the speech reproduction to render itimpossible to carry out consecutive reproduction of the contents.

Thus, in the present embodiment, if, in case of consecutive reproductionof the encrypted contents, the processing time for the processing forfringe demodulation for the encrypted contents reproduced next is longerthan the usual range such that consecutive reproduction cannot beguaranteed with the usual buffer capacity setting values, another buffercapacity, retained to be larger than the usual buffer capacity (referredto below as a ‘buffer capacity for coping with long-time processing’) isset.

Such change in the buffer capacity setting may be implemented bychanging each area setting of the buffers 1 to 3 in the buffer area 20 ain the RAM 20, under control by the CPU 11. In short, if an areacorresponding to the capacity A is allocated to each of the buffers 1 to3 as a usual buffer capacity, an area corresponding to a differentcapacity B larger than the capacity A is allocated to each of thebuffers 1 to 3 in setting the buffer capacity for coping with long-timeprocessing.

The timing chart of FIG. 12 shows the operations in case the buffercapacity for coping with long-time processing is set, and contents B arereproduced in succession to contents A with shorter reproduction time,as in the case of FIG. 11.

In this case, the processing of decryption/demodulation commences at atime point t2, in succession to the processing for fringe demodulationfor the contents A for the time period t1-t2. With the progress in thisprocessing of decryption/demodulation, writing is carried out, beginningfrom the buffer 1, as from the same time point t2. It may be seen that,since each of the buffers 1 to 3 is set to a capacity larger than theusual capacity, the time needed until the end of writing in the buffer 1is longer. Hence, the time duration as from time point t2 until timepoint t3 of start of the transfer processing to the reproducingoutputting system for the contents A is longer than the time period oft2-t3 shown in FIG. 12. In short, the standby time until actual start ofreproduction/outputting of the speech in starting the reproductionbecomes longer.

In this case, data is shown to be stored only in the buffer 3, out ofthe buffers 1 to 3, in a stage of a time point t4 when the processing ofdecryption/demodulation for the contents A, for example, has come to aclose. Hence, as from the time point t4, the operation of reading outand reproducing/outputting the data stored in the buffer 3 is carriedout as the transfer processing to the reproducing/outputting system forthe contents A proceeds. This readout operation is carried out duringthe time period of the reproducing time TL corresponding to the capacityof the buffer 3. It is noted that the unit reproducing time TLcorresponds to the buffer capacity for coping with long-time processingand hence is longer than the unit reproducing time Ts corresponding tothe usual buffer capacity.

In short, with the setting of the buffer capacity for coping withlong-time processing, the time period as from the end of the processingof decryption/demodulation until the end of the transfer processing tothe reproducing/outputting system is protracted. In short, the timeduration of the time period t4-t6 in FIG. 12 is longer than the timeperiod t4-t6 in FIG. 11.

In this case, the processing for fringe demodulation for the contents B,carried out as from the time point t4, again comes to a close after thetime equivalent to that in FIG. 11, or at a time point t5. However,since the time period t4-t6 is protracted, as described above, the timepoint t5 when the processing for fringe demodulation for the contents Bcomes to a close is temporally forward of the time point t6 when thetransfer processing to the reproducing outputting system for thecontents A comes to a close.

In this case, the processing of decryption/demodulation for the contentsB commences at the time point t5 when the processing for fringedemodulation for the contents B comes to a close, while the transferprocessing to the reproducing/outputting system for the contents Bcommences after lapse of certain time as from this time point t5, thatis, at the time point t6. In short, the transfer processing to thereproducing outputting system for the contents B commences directlyafter the end of the transfer processing to the reproducing outputtingsystem for the contents A, thus assuring consecutive reproduction of thecontents A and B.

It will be understood that, by setting the different buffer capacity toa value larger than the usual capacity value, it is possible to maintainthe continuity of the reproduced sound even in such case the time longerthan the usual time is needed for the processing for fringedemodulation.

With the present embodiment, described above, switching is made betweenthe usual buffer capacity and the buffer capacity for coping withlong-time processing. This switching of the buffer capacity is to becarried out by the CPU 11 in accordance with e.g. a program forreproducing encrypted contents.

In short, when the CPU 11 has recognized that the processing time neededfor the processing for fringe demodulation for contents data reproducednext to contents data retained to be currently reproduced, the CPU setsthe usual buffer capacity. In this case, it is possible to maintain thecontinuity of the reproduced sound for the encrypted contents,reproduced in succession, as explained for example with reference toFIG. 10.

Conversely, when the CPU 11 has recognized that the processing timeneeded for the processing for fringe demodulation for contents datareproduced next is so long as to exceed the usual range, the CPUswitches the buffer capacity to the buffer capacity for coping withlong-time processing. Hence, it is possible to maintain the continuityof the reproduced sound for the encrypted contents with shortreproducing time, as shown in FIG. 12.

In determining whether the processing time for fringe data is within orexceeds a usual range, it is sufficient if the type, such as contents ordata size of fringe data or the encoding for compression, is recognizedfrom e.g. the information stored in a header appended to the fringedata, and to get the processing for estimating the processing time forthe fringe data executed based on the results of recognition.

In the case shown in FIG. 12, the change of the buffer capacityresponsive to the fringe data processing time is to be made at a timingof starting the buffering of data of the encrypted contents temporallydirectly forward in the reproduction sequence of the encrypted contentsrelated to the processing time of the fringe data. This, however, ismerely illustrative.

It may be said that, for enabling consecutive reproduction of contentsfor coping with the case where the processing time for the fringe dataexceeds the usual range, it is sufficient if the buffer capacity isswitched to that for coping with long-time processing at a timing acertain time before the start of the processing of the fringe data atthe latest, for example even during reproduction of the directlyprevious encrypted contents.

Thus, it may be contemplated to effect capacity switching sequentially,beginning from a buffer which has become void, at a reasonable timing apreset time before the start of the processing of the fringe data ofinterest, even during reproduction/outputting of data of encryptedcontents directly previous in the reproduction sequence to encryptedcontents associated with the fringe data.

It may also be said that there is no particular limitation to the timingof giving the decision on the processing time for fringe data, if onlythe decision is given at a preset timing previous to the timing ofchanging the buffer capacity.

The present invention is not limited to the above-described embodiments

For example, in the above explanation of the preferred embodiments, thebuffer capacity switching is carried out in two steps. The buffercapacity switching may also be carried out in three or more steps,depending on, for example, the time needed for processing the fringedata.

In the above-described embodiments, the area sizes of the buffers 1 to 3are allocated in the buffer area 20 a in the RAM 20. Alternatively, amemory device, operating as a buffer, may be provided in addition to theRAM 20. In such case, it may be contemplated to provide separately amemory device having capacities as the buffers 1 to 3 corresponding tothe usual buffer capacity and another memory device having capacities asthe buffers 1 to 3 corresponding to the buffer capacity for coping withlong-time processing. If, in the buffer write/readout processing, theusual buffer capacity, or the buffer capacity for coping with long-timeprocessing, is set, the write/readout for the former type memory deviceor the write/readout for the latter type memory device, may be executed,respectively. With this configuration, it is similarly possible torealize the operation of changing the capacity of data storage meansaccording to the present invention.

In addition, in the above-described embodiment, the encoding performedon the contents to be reproduced is not limited to the encoding forcompression or to the encoding for encryption. In keeping therewith, theactual processing for decrypting the contents or for pre-decryptingprocessing related to the decrypting processing may suitably be changed.

The contents encoded may, for example, be video data instead of audiodata.

In the foregoing explanation, it is the program run on the CPU 11 thatimplements the operations according to the present invention. Thisprogram is installed/stored e.g. in the HDD 21 or ROM 13.

Alternatively, the program may be stored (recorded), transiently orpermanently, in a removable recording medium, such as a CD-ROM (CompactDisc Read Only Memory), an MO (magnet optical) disc, a DVD (DigitalVersatile Disc), a magnetic disc or a semiconductor memory. Thisremovable recording medium may also be provided as so-called packagesoftware.

For example, in the present embodiment, the program may be recorded in arecording medium that can be coped with by the medium drive 19 andprovided as package software. By so doing, the recording and/orreproducing apparatus 1 is able to read out the program from therecording medium by the medium drive 19 and installed (stored) in theHDD 21 or in the ROM 13. Moreover, since the program is supplied as thepackage software, the program of the system embodying the presentinvention may be installed in e.g. a general-purpose personal computer.

In addition to being installed from the above-described removablerecording medium, the program may also be downloaded e.g. from a server,having stored the program, over a network, such as LAN (Local AreaNetwork) or the Internet.

Furthermore, an update program for late addition of the function(s)embodying the present invention may be constructed and distributed aspackage medium or over the network. It is only sufficient for a user toacquire this update program and install it on an environment where thepreexisting systems are preinstalled.

The present invention is not limited to the above embodiments, explainedwith reference to the drawings, and various changes, substitutions orequivalents that may be undertaken by those skilled in the art may bemade without departing from the scope and the purport of the inventionas defined in the claims.

INDUSTRIAL APPLICABILITY

The present invention has, as the subject of information processing,unit data (contents data) reproduced on executing the processing ofdecoding of decryption/demodulation) and pre-processing of decoding thatneeds at any rate to be carried out at a timing prior to the start ofthe processing of decoding.

In reproducing/outputting the plural unit data in succession, thepre-processing of decoding for unit data reproduced next to the unitdata currently reproduced/output is started at timing after the end ofthe processing of decoding for the unit data currentlyreproduced/output. The pre-decoding for the unit data reproduced next iscarried out during the time the reproduction/outputting of the unit datacurrently reproduced/output is continued by reading out data stored instorage means (storage area).

By so doing, there is no time period when the processing of decoding onthe unit data currently reproduced and pre-ecoding processing on theunit data currently reproduced and the processing of decoding on theunit data to be reproduced next are carried out simultaneously inparallel. This assures that there is no increase in the processing loadcaused by simultaneous execution of the pre-decoding processing and theprocessing of decoding, such that the processing of decoding may becarried out at an optimum speed. Moreover, even when the processingother than the processing of reproducing unit contents is carried out inparallel, there may be certain allowance in the processing capabilitybecause the pre-decoding processing and the processing of decoding arenot carried out simultaneously.

Thus, according to the present invention, there is no risk that theprocessing, currently reproduced, including the reproduction/outputtingof the unit data, becomes unstable.

Moreover, according to the present invention, the processing of decoding(processing of decryption/demodulation) on unit data (contents data),and the pre-decoding processing, which is the processing required to becarried out at timing prior to start of the processing of decoding, andwhich becomes necessary in connection with the reproduction of the unitdata, are carried out. If the unit data are to be reproduced/output insuccession, the pre-decoding processing for unit data reproduced next tothe unit data currently reproduced/output is commenced at timing afterthe processing of decoding of the unit data currently reproduced andoutput. The pre-decoding processing for the unit data, reproduced next,is carried out by reading out data stored in the storage means, duringthe time the reproduction/outputting of the unit data currentlyreproduced/output is continued.

First of all, with this configuration, there is no time period duringwhich the processing of decoding on the unit data currentlyreproduced/output and the pre-decoding processing on the unit datareproduced next are carried out simultaneously in parallel. This assuresthat there is no increase in the processing load caused by simultaneousexecution of the pre-decoding processing and the processing of decoding,with the result that the processing of decoding may be carried out at anoptimum speed.

In addition, the data capacity of the storage means is changed withinthe time period the decoded data of unit data currentlyreproduced/output is stored in storage means, depending on the durationof the processing time, retained to be needed for the pre-decodingprocessing for the unit data reproduced/output next.

By so doing, the time duration of the reproduction/outputting of theunit data after the end of the processing of decoding may also bechanged, depending on the duration of the processing time retained to beneeded for the pre-decoding processing. In short, even if the processingtime needed for pre-decoding processing is relatively long, thesuccessive reproduction/outputting time of unit data, related to theprocessing time, may be achieved, with the result that the successiveoutputting of the unit data may be maintained.

1. An information processing apparatus comprising processing means forcarrying out at least a processing of decoding encoded unit data and apre-decoding processing related to said unit data, said pre-decodingprocessing being carried out prior to said processing of decoding;storage means where decoded data obtained on said processing of decodingare written and transiently stored; and outputting means from which thedecoded data stored in said storage means is continuously read out andoutput as data for reproduction/outputting; said processing meanscommencing the processing of decoding of said unit data after the end ofthe pre-ecoding processing related to said unit data.
 2. The informationprocessing apparatus according to claim 1 wherein, if second unit datais reproduced/output next to first unit data, said processing meanscommences pre-decoding processing related to said second unit data afterthe end of the processing of decoding of said first unit data.
 3. Theinformation processing apparatus according to claim 1 wherein saidstorage means includes a plurality of transient storage areas; saidprocessing means sequentially writing decoded data, obtained onprocessing of decoding, in said plural transient storage areas, from onedata capacity of said transient storage area to another; said outputtingmeans reading out the written decoded data each time said decoded datais written in said transient storage area and outputting the data asdata for reproduction/outputting.
 4. The information processingapparatus according to claim 1 wherein said processing of decoding forunit data is the processing of decryption and/or demodulation; andwherein said pre-decoding processing related to unit data is tampercheck processing for said unit data.
 5. The information processingapparatus according to claim 1 wherein said processing of decoding forunit data is the processing of decryption and/or demodulation; andwherein said pre-ecoding processing related to unit data is processingof decryption and/or demodulation for relevant data pertinent to saidunit data.
 6. The information processing apparatus according to claim 1wherein said storage means includes at least one transient storage areaand data capacity changing means for changing the data capacity of saidtransient storage area depending on the length of reproducing time forsaid unit area.
 7. The information processing apparatus according toclaim 1 wherein said storage means includes a plurality of transientstorage areas; and data capacity changing means for changing the datacapacity of said transient storage area of said storage means; said datacapacity changing means changing the data area of said transient storagearea depending on the duration of processing time needed for saidpre-decoding processing relevant to said unit data.
 8. The informationprocessing apparatus according to claim 7 wherein, if said pre-decodingprocessing relevant to unit data is the processing of decryption and/ordemodulation of relevant data, related to said unit data, the durationof the processing time needed for said pre-decoding processing isestimated based on the ancillary information added as relevant data. 9.The information processing apparatus according to claim 7 wherein saidstorage means includes a plurality of sets of transient storage areas,each set being made up of a plurality of transient storage areas andbeing different in storage capacities; said data capacity changing meansselecting one of transient storage areas of said plural sets dependingon the duration of the processing time retained to be needed for saidpre-decoding processing.
 10. An information processing method comprisingpre-decoding processing relevant to encoded unit data; processing ofdecoding for decoding said unit data after the end of said pre-decodingprocessing; processing of storage for transiently storing decoded dataobtained on said processing of decoding; and outputting processing forsuccessively reading out said decoded data transiently stored by saidprocessing of storage and for outputting the read-out decoded data asdata for reproduction/outputting.
 11. The information processing methodaccording to claim 10 wherein, when second unit data isreproduced/output next to first unit data, pre-decoding processingrelevant to second unit data is commenced after the end of theprocessing of decoding of first unit data.
 12. The informationprocessing method according to claim 10 wherein said processing ofdecoding is the processing of decryption and/or demodulation and whereinsaid pre-decoding processing is tamper check processing for said unitdata.
 13. The information processing method according to claim 10wherein said processing of decoding is the processing of decryptionand/or demodulation and wherein said pre-decoding processing is theprocessing of decryption and/or demodulation for relevant data relatedto said unit data.
 14. The information processing method according toclaim 10 wherein said processing of storage is performed on storagemeans having at least one transient storage area; said method furthercomprising processing of changing the data capacity of said transientstorage area depending on the duration of the reproduction time of saidunit data.
 15. The information processing method according to claim 10wherein said processing of storage is carried out for storage meanshaving a plurality of transient storage areas, and wherein the methodfurther comprises data capacity change processing for changing the datacapacity of said transient storage area depending on the duration of theprocessing time retained to be needed for pre-ecoding processingrelevant to said unit data.
 16. The information processing methodaccording to claim 15 wherein, if said pre-decoding processing relevantto said unit data is the processing of decryption and/or demodulationfor relevant data related to unit data, the duration of the processingtime, retained to be needed for said pre-decoding processing, isestimated based on the ancillary information annexed to said relevantdata.
 17. The information processing method according to claim 10wherein said storage means includes a plurality of sets of transientstorage areas, each set being made up of a plurality of transientstorage areas and being different in storage capacities; said datacapacity changing means selecting one of transient storage areas of saidplural sets depending on the duration of the processing time retained tobe needed for said pre-decoding processing.